Combined effects of ethanol and hyperbaric air on body sway and heart rate in man.

Eight amateur divers took part in crossover experiments to study the combined effects of ethanol (0.72 g/kg b.wt.) and hyperbaric air (4 and 6 ATA) on heart rate and body-sway movements. Body sway with open and closed eyes was measured in lateral and sagittal directions by a statometer device. In the alcohol condition, there was an initial increase in body sway corresponding to the acute phase of ethanol intoxication. At a mean blood alcohol concentration of 0.77 mg/ml, this increase in body sway was statistically significant (P less than 0.01) compared with the alcohol-free condition. At 90 min from start of drinking, body sway scores at 1 ATA were not significantly different from alcohol-free measurements. On raising the pressure to 4 and 6 ATA, increased body sway occurred in both alcohol and alcohol-free conditions and, moreover, the rate of increase was more extreme in the alcohol condition. Significant pressure-alcohol interactions were established, suggesting a potentiating action of alcohol on the increase in body sway induced by acute exposure to high pressures of air. Heart-rate measurements with and without alcohol were not significantly different, although increases in ambient pressure caused a drop in heart rate in both conditions.